Lens barrel, image-capturing device, and method for controlling lens barrel

ABSTRACT

A lens barrel in which tilt adjustment can be made depending on the position of a lens unit in the optical axis direction. This lens barrel includes: at least three guide bars provided so as to extend along the optical axis direction; a driving unit that respectively drives the at least three guide bars in the optical axis direction; a lens frame holding unit that holds an image-capturing lens, the lens frame holding unit being attached to at least three guide bars and being driven in the optical axis direction by the at least three guide bars; and a control unit that controls said at least three linear actuators so as to adjust the respective drive amounts in the optical axis direction of the at least three guide bars and to tilt the lens frame holding unit from a direction orthogonal to the optical axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. continuation application filed under 37C.F.R. 1.53(b) claiming priority benefit of U.S. patent application Ser.No. 14/754,399, filed Jun. 29, 2015, now U.S. Pat. No. 9,488,797, whichis a continuation of U.S. application Ser. No. 14/123,006, filed Feb.18, 2014, now U.S. Pat. No. 9,103,952. U.S. application Ser. No.14/123,006 further claimed the benefit, under 35 U.S.C. Section 371, ofPCT International Application No. PCT/JP2012/068447, filed Jul. 20,2012, which claimed foreign priority benefit to Japanese Application No.2011-158865, filed Jul. 20, 2011 and Japanese Application No.2011-158866, filed Jul. 20, 2011 in the Japanese Patent Office, thedisclosures of which are hereby incorporated by reference.

BACKGROUND

1. Field

The present invention relates to a lens barrel, an image-capturingdevice, and a method for controlling the lens barrel.

2. Description of Related Art

A lens barrel generally includes a plurality of lenses (lens units). Inthese lens units, an optical axis of the lens may be tilted with respectto an optical axis of the lens barrel due to assembling errors or thelike.

Conventionally, when lenses are assembled, in order to adjust such atilt of a lens (that is, to perform tilt adjustment), a washer having anappropriate width is inserted between a lens frame and a lens holdingframe that holds the lens frame (see Patent Document 1).

Moreover, an internal focusing zoom lens that changes a focal positionof an optical system by changing the distance between a plurality oflenses to change the magnification of the optical system to move anintermediate lens of the optical system is known (see Patent Document2).

[Patent Document 1] Japanese Unexamined Patent Application, PublicationNo. 2006-03837

[Patent Document 2] Japanese Unexamined Patent Application, PublicationNo. 2000-89086

SUMMARY

According to the adjustment method disclosed in Patent Document 1, thetilt is not changed after tilt adjustment is performed before shipping.However, the tilt direction may be different depending on the positionof the lens in the optical axis direction.

Moreover, in Patent Document 2, when the intermediate lens is driven bythree guide bars, the guide bar may be constrained redundantly.

An object of the present invention is to provide a lens barrel, animage-capturing device and a method for controlling the lens barrel inwhich tilt adjustment can be made depending on the position of a lens inan optical axis direction.

Another object of the present invention is to provide a lens barrel andan image-capturing device capable of stably holding a lens frame.

Means for Solving the Problems

The present invention solves the problems by the following means. Forbetter understanding, although embodiments of the present invention aredescribed with corresponding constituent components designated bycorresponding reference numerals, the present invention is not limitedto this.

According to a first aspect of the present invention, there is provideda lens barrel including: three guide bars provided so as to extend in anoptical axis direction; three actuators that drive the three guide barsin the optical axis direction, respectively; a lens frame that holds animage-capturing lens and that is attached to the three guide bars anddriven in the optical axis direction by the three guide bars; and acontrol unit that adjusts driving amounts of the three guide bars in theoptical axis direction and controls the three linear actuators so thatthe lens frame is tilted from a direction orthogonal to the opticalaxis.

In the first aspect, the lens barrel may further include: a fixing unitthat holds the three guide bars so as to be movable in the optical axisdirection; and a position detecting device that detects positions in theoptical axis direction of the three guide bars in relation to the fixingunit, wherein the control unit may be configured to detect a positionand the tilt of the lens frame in relation to the fixing unit from thepositions of the three guide bars detected by the position detectingdevice.

In the first aspect, three openings corresponding to the respectiveguide bars may be formed in the lens frame, a body portion having alarger diameter than the corresponding opening and a small-diameterportion provided on a side of the body portion closer to a subject andconfigured to be inserted into the opening may be formed in an endportion of the three guide bars, respectively, a stopper member having alarger diameter than the opening may be attached from outside to thesmall-diameter portion in a state where the small-diameter portion isinserted into the opening, and a biasing member that biases the lensframe in the optical axis direction may be disposed on an outercircumference of the small-diameter portion.

In the first aspect, a first opening of the three openings and asmall-diameter portion inserted into the first opening may be fittedwith a minimum necessary gap, a second opening among the three openingsmay be a U-shaped groove or long hole of which the opening length in afirst direction that is vertical to the optical axis and extends towardthe first opening is larger than an opening length in a second directionthat is vertical to the optical axis and orthogonal to the firstdirection, and the second opening and a small-diameter portion insertedinto the second opening may be fitted with a minimum necessary gap inthe second direction, and a third opening and a small-diameter portioninserted into the third opening may have a sufficient gap necessary foravoiding redundant constraint.

In the first aspect, the lens frame may move in the optical axisdirection during zooming or focusing.

In the first aspect, the control unit may change the driving amounts ofthe three guide bars in the optical axis direction and may change adirection and an amount of tilt of the lens frame from a directionorthogonal to the optical axis based on the position of the lens framein the optical axis direction during zooming or focusing.

In the first aspect, the lens barrel may further include a fixedcylinder that holds the three guide bars so as to be movable in theoptical axis direction.

In the first aspect, the three guide bars have different thicknesses.

According to a second aspect of the present invention, there is providedan image-capturing device including the lens barrel.

According to a third aspect of the present invention, there is provideda method for controlling a lens barrel including: three guide barsprovided so as to extend in an optical axis direction; three actuatorsthat drive the three guide bars in the optical axis direction,respectively; and a lens frame that holds an image-capturing lens andthat is attached to the three guide bars and driven in the optical axisdirection by the three guide bars, the method including: adjustingdriving amounts of the three guide bars in the optical axis directionand controlling the three linear actuators so that the lens frame istilted from a direction orthogonal to the optical axis.

According to a fourth aspect of the present invention, there is provideda lens barrel including: first, second, and third guide bars that extendin an optical axis direction and at least one thereof is driven in theoptical axis direction by a driving mechanism; and a lens holding unitthat holds an image-capturing lens and has first, second, and thirdopenings in which engagement portions of the first, second, and thirdguide bars are inserted, respectively, wherein the first opening is afitting hole in which a position of the first guide bar of the lensholding unit is fixed when the engagement portion of the first guide baris inserted in the first opening, the second opening is a U-shapedgroove or long hole of which the opening length in a first directionthat is vertical to the optical axis and extends toward the firstopening is larger than a diameter of the engagement portion of thesecond guide bar, and in which a position of the second guide bar in asecond direction that is vertical to the optical axis and is vertical tothe first direction is fixed, and the third opening is an insertion holewhich has a larger diameter than the diameter of the engagement portionof the third guide bar and in which the engagement portion can beinserted even when the third guide bar is shifted within a certain rangefrom the center of the third opening.

According to a fifth aspect of the present invention, there is providedan image-capturing device including the lens barrel.

According to the present invention, it is possible to provide a lensbarrel, an image-capturing device and a method for controlling the lensbarrel in which optimal tilt adjustment can be made depending on theposition of a lens unit in an optical axis direction.

Moreover, it is possible to provide a lens barrel and an image-capturingdevice capable of avoiding redundant constraint of the guide bar by thelens holding unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram conceptually illustrating a camera which is a firstembodiment according to the present invention.

FIG. 2 is a diagram illustrating a lens frame of a lens barrel of FIG. 1when seen from a direction indicated by A-A.

FIG. 3 is a cross-sectional view of the lens barrel taken along line B-Bin FIG. 2.

FIG. 4 is a cross-sectional view of the lens barrel taken along line C-Cin FIG. 2.

FIGS. 5A through 5C are diagrams illustrating a state where a secondlens frame is held by a guide bar, in which FIG. 5A illustrates aholding state of a first guide bar, FIG. 5B illustrates a holding stateof a second guide bar, and FIG. 5C illustrates a holding state of athird guide bar.

FIG. 6 is a diagram illustrating only the lens frame of FIG. 2.

FIG. 7 is a diagram schematically illustrating a camera which is thefirst embodiment according to the present invention.

FIG. 8 is a diagram of a lens frame of a lens barrel of FIG. 7 when seenfrom a direction indicated by A-A.

FIG. 9 is a cross-sectional view of the lens barrel taken along line B-Bin FIG. 8.

FIG. 10 is a cross-sectional view of the lens barrel taken along lineC-C in FIG. 8.

FIGS. 11A through 11C are diagrams illustrating a state where a secondlens frame is held by a guide bar, in which FIG. 11A illustrates aholding state of a first guide bar, FIG. 11B illustrates a holding stateof a second guide bar, and FIG. 11C illustrates a holding state of athird guide bar.

FIG. 12 is a diagram illustrating only the lens frame of FIG. 8.

DESCRIPTION OF EMBODIMENTS Explanation of Reference Numerals

-   1: CAMERA-   10: CAMERA BODY-   100: LENS BARREL-   101: FIRST GUIDE BAR-   102: SECOND GUIDE BAR-   103: THIRD GUIDE BAR-   125A, 125A′: FIRST LINEAR ACTUATOR-   125B, 125B′: SECOND LINEAR ACTUATOR-   125C, 12CA′: THIRD LINEAR ACTUATOR-   201, 201′: FIRST HOLE-   202, 202′: HOLE-   203, 203′: THIRD HOLE-   127, 127′: POSITION DETECTING UNIT-   130: ZOOM RING-   133: ZOOM RING ROTATION AMOUNT DETECTING UNIT-   190: LENS FRAME-   L1, L2, L3, L4, L5: LENS-   OA: OPTICAL AXIS

Hereinafter, embodiments of the present invention will be described withreference to the drawings and the like.

FIG. 1 is a diagram conceptually illustrating a camera 1 which is afirst embodiment according to the present invention.

In FIGS. 1 and 2, an XYZ orthogonal coordinate system is provided forbetter explanation and understanding. In this coordinate system, adirection pointing to the left side as seen from a photographer at theposition (hereinafter referred to as a normal position) of a camera whenthe photographer takes images in a landscape orientation with theoptical axis OA orientated horizontally is referred to as a positive Xdirection, and a direction pointing to the upper side at the normalposition is referred to as a positive Y direction.

Moreover, a direction pointing to a subject at the normal position isreferred to as a positive Z direction. This positive Z direction is alsoreferred to as a subject side, and a negative Z direction is alsoreferred to as an image side. Further, movement in a direction parallelto the optical axis OA (that is, the Z-axis) is referred to as “straightmovement,” and revolution about the optical axis OA is referred to as“rotation.”

A camera 1 includes a camera body 10 and a lens barrel 100.

The lens barrel 100 is a so-called zoom lens of which the focal lengthcan be adjusted. The lens barrel 100 includes a plurality of lenses (L1to L5) that forms an imaging optical system and an aperture mechanism222 that changes an opening size thereof to adjust the amount ofincident light.

The lens barrel 100 further includes a lens mount 113 that detachablyengages with a camera mount CM and is detachably attached to the camerabody 10 with the lens mount 113 interposed. In this manner, the camera 1can capture images while replacing with other lens barrels depending onthe purpose.

The camera body 10 includes a quick return mirror 11, a finder screen12, a pentagonal prism 13, an eyepiece optical system 14, a shutter 15,an image-capturing element 16, a display device 17, a control device 18,a distance measuring sensor 19, and the like.

The quick return mirror 11 is a mirror that is pivotably provided in thecamera body 10 so that an optical path of a subject image focused by thelens barrel 100 is bent toward the finder screen 12. The quick returnmirror 11 moves to a withdrawn position (indicated by a two-dot chainline in FIG. 1), at which entering of a subject beam to theimage-capturing element 16 is not impaired, in response to a releaseoperation.

Moreover, a half mirror is formed in a portion of the quick returnmirror 11, and a sub-mirror 11A is arranged on a portion of a rearsurface of the quick return mirror 11 corresponding to the half mirrorportion. The sub-mirror 11A guides a subject image beam having passedthrough the half mirror portion of the quick return mirror 11 toward thedistance measuring sensor 19. The sub-mirror 11A moves along the rearsurface of the quick return mirror 11 with movement of the quick returnmirror 11 toward the withdrawn position.

The finder screen 12 is a screen on which a subject image reflected bythe quick return mirror 11 is formed and is disposed between the quickreturn mirror 11 and the pentagonal prism 13.

The pentagonal prism 13 is a prism having a pentagonal cross-sectionalshape and is arranged above the camera body 10 posed in a horizontalattitude. The pentagonal prism 13 guides an image formed on the finderscreen 12 toward the eyepiece optical system 14 as an erected image.

The eyepiece optical system 14 is an optical system for observing thesubject image converted into an erected image by the pentagonal prism 13at an enlarged scale and is disposed on an image side (photographerside) of the pentagonal prism 13.

The shutter 15 is opened and closed in response to a release operationto control an exposure period of the subject image beam formed in theimage-capturing element 16.

The image-capturing element 16 is a photoelectric conversion elementsuch as, for example, a CCD for converting the subject image formed bythe lens barrel 100 into an electrical signal. The image-capturingelement 16 is provided inside the camera body 10 in a state where alight receiving surface thereof is orthogonal to the optical axis OA.

The display device 17 includes a display panel of liquid crystal or thelike provided on the photographer side outside the camera body 10. Thedisplay device 17 displays a captured image and information related toimage-capturing such as an exposure period on the display panel.

The control device 18 is configured to include a CPU or the like andcontrols the above-described respective constituent components of thecamera body 10 and the lens barrel 100 attached to the camera body 10 ina centralized manner.

The distance measuring sensor 19 detects information on the distance toa subject from the subject image beam incident via the sub-mirror 11Aand outputs the distance information to the control device 18.

The camera body 10 is integrally combined with the lens barrel 100 asdescribed above to form the camera 1. In the combined state, the controldevice 18 of the camera body 10 and a power source (not illustrated) areconnected to the lens barrel 100 by a connection terminal (notillustrated), and the control device 18 is connected to a barrel controlunit 123 described later of the lens barrel 100.

During image-capturing, the camera 1 operates in the following manner.

When a shutter button (not illustrated) provided in the camera body 10is pressed (released), the quick return mirror 11 moves to the withdrawnposition. The shutter 15 is opened and closed according to the releaseoperation so that the subject image beam is exposed to theimage-capturing element 16 for a predetermined period. Theimage-capturing element 16 converts the subject image beam into anelectrical signal to capture an image. The image data captured by theimage-capturing element 16 is recorded in a recording unit (notillustrated).

Image-capturing is performed in this manner, and during theimage-capturing, the control device 18 controls the aperture mechanism222 based on photometric information obtained by a photometric sensor(not illustrated) included in the camera body 10, and during anauto-focus operation, transmits the driving amount of linear actuators125A, 125B, and 125C based on the distance information from the distancemeasuring sensor 19 to the barrel control unit 123.

Next, the lens barrel 100 will be described in detail with reference toFIGS. 2 to 6 in addition to FIG. 1.

FIG. 2 is a diagram of the lens frame 190 of the lens barrel 100 of FIG.1 when seen from the direction indicated by A-A. FIG. 3 is across-sectional view of the lens barrel 100 taken along line B-B in FIG.2. FIG. 4 is a cross-sectional view of the lens barrel 100 taken alongline C-C in FIG. 2. FIG. 1 is a cross-sectional view taken along lineD-D in FIG. 2.

The lens barrel 100 includes five lens units L1, L2, L3, L4, and L5 thatare sequentially arranged along the common optical axis OA as describedabove. The lenses L1, L2, L3, L4, and L5 are held by a first lens frame160, a second lens frame 190, a third lens frame 70, a fourth lens frame80, and a fifth lens frame 90, respectively.

The lens barrel 100 is an internal focusing zoom lens that uses the lensL2 as a focusing lens, and an overall focal length of the lens barrel100 changes continuously when the lenses L1, L2, L3, L4, and L5 move bya predetermined amount in the optical axis OA direction (Z direction).

The lens L2 is a focus lens of which the focal position changes when thelens L2 moves in the optical axis OA direction. Further, the fourth lensframe 80 that holds the lens L4 includes the aperture mechanism 222 thatchanges the diameter of the optical path of the optical system includingthe lens L4.

The lens barrel 100 includes a fixed cylinder 110 to which the lensmount 113 that is detachable from the camera body 10 is fixed. An innercylinder 140, a middle cylinder 150, an outer cylinder 161, and a zoomring 130 which are at the same axis are disposed on the subject side ofthe fixed cylinder 110 in that order from the inner side.

A cam cylinder 170 that is rotatable in relation to the fixed cylinder110 is disposed inside the fixed cylinder 110. Moreover, three guidebars (first guide bar 101 (see FIGS. 1, 2, and 3), second guide bar 102(see FIGS. 2 and 3), and third guide bar 103 (see FIGS. 2 and 4))disposed in parallel to the optical axis OA are disposed on a furtherinner side of the cam cylinder 170. In the present embodiment, thesethree guide bars 101, 102, and 103 have the same diameter; however, thepresent invention is not limited to this.

The fixed cylinder 110 includes a straight groove 111, a cam pin 112,the lens mount 113, a first supporting portion 114A, a second supportingportion 114B, and a third supporting portion 114C. The straight groove111 extends in the optical axis OA direction of the lens barrel 100. Thecam pin 112 protrudes inward in the radial direction from the innercircumferential surface of the fixed cylinder 110 and engages with a camgroove 173 described later of the cam cylinder 170.

When the lens mount 113 engages with the camera mount CM, the fixedcylinder 110 is fixed to the camera body 10. In the fixed cylinder 110fixed to the camera body 10, a mount surface 115 at a rear end of thefixed cylinder 110 makes close contact with an front surface of thecamera mount CM of the camera body 10. As a result, the entire lensbarrel 100 is aligned with respect to the camera body 10.

The supporting portions 114A, 114B, and 114C protrude inward in theradial direction from the inner circumferential surface of the fixedcylinder 110 to support the guide bars 101, 102, and 103, respectively.

The first supporting portion 114A that supports the first guide bar 101disposed on the upper side in FIGS. 1 and 3 includes a fitting hole117BA having a shape that is complementary to the shape of the outercircumference of the first guide bar 101. The first guide bar 101 issupported by being inserted in the fitting hole 117B.

The second supporting portion 114B supporting the second guide bar 102and the third supporting portion 114C supporting the third guide bar 103have the same configuration as the first supporting portion 114A, andthus the description thereof will not be provided.

The inner cylinder 140 includes a cam follower 142, a clearance hole144, a straight groove 146, and an engagement projection 148. The camfollower 142 protrudes inward in the radial direction of the lens barrel100 from a portion near the rear end of the inner cylinder 140. Thestraight groove 146 extends in the optical axis OA direction of the lensbarrel 100. The engagement projection 148 also protrudes outward in theradial direction of the lens barrel 100.

The cam follower 142 passes through the straight groove 111 and engageswith a cam groove 171 described later of the cam cylinder 170. As aresult, when the cam cylinder 170 rotates, rotation of the innercylinder 140 about the optical axis OA is restricted. Moreover, drivingforce that moves the inner cylinder 140 in the optical axis OA directionis transmitted from the cam groove 171 to the cam follower 142.

The clearance hole 144 is disposed at a position different from that ofthe straight groove 146 in relation to the circumferential direction ofthe lens barrel 100. A cam follower 172 described later of the camcylinder 170 is inserted into the clearance hole 144.

The middle cylinder 150 includes a cam follower 152, a cam groove 154, astraight groove 156, and an engagement circumferential groove 158. Thecam follower 152 protrudes outward in the radial direction of the lensbarrel 100 and engages with a guide groove 132 of the zoom ring 130. Thecam groove 154 extends with an inclination with respect to the opticalaxis OA.

The straight groove 156 is disposed at a position different from that ofthe cam groove 154 in relation to the circumferential direction of thelens barrel 100. The straight groove 156 extends in the optical axis OAdirection and engages with a cam follower 172 described later of the camcylinder 170.

The engagement circumferential groove 158 is formed on the innercircumferential surface of the middle cylinder 150 so as to extend alonga surface orthogonal to the optical axis OA. The engagementcircumferential groove 158 engages with the engagement projection 148 ofthe inner cylinder 140. As a result, the middle cylinder 150 is freelyrotatable about the optical axis OA independently from the innercylinder 140 while moving integrally with the inner cylinder 140 inrelation to the optical axis OA direction.

The outer cylinder 161 includes a cam follower 162. The cam follower 162protrudes inward in the radial direction of the lens barrel 100 andengages with the cam groove 154 of the middle cylinder 150 and thestraight groove 146 of the inner cylinder 140. As a result, when themiddle cylinder 150 rotates about the optical axis OA, the cam follower162 transmits driving force in the optical axis OA direction to theouter cylinder 161 while restricting the outer cylinder 161 fromrotating about the optical axis OA.

Moreover, the outer cylinder 161 is combined with the first lens frame160 that holds the lens L1. As a result, when the outer cylinder 161moves in the optical axis OA direction, the lens L1 also moves along theoptical axis OA.

The cam cylinder 170 is rotatably disposed inside the fixed cylinder110. The cam cylinder 170 includes a plurality of cam grooves 171 and173 and the cam follower 172. The cam grooves 171 and 173 are formedwith an inclination with respect to the optical axis OA, respectively.The cam groove 171 engages with the cam follower 142 of the innercylinder 140. The cam groove 173 engages with the cam pin 112 of thefixed cylinder 110.

The cam follower 172 protrudes outward in the radial direction by aconnecting member 174 and engages with the straight groove 156 of themiddle cylinder 150 by passing through the clearance hole 144 of theinner cylinder 140. As a result, when the middle cylinder 150 rotatesabout the optical axis OA, the driving force that rotates the camcylinder 170 is transmitted from the cam follower 172 to the camcylinder 170.

The cam cylinder 170 further includes other cam grooves (notillustrated) or the like in order to produce the driving force thatmoves the third, fourth, and fifth lens frames 70, 80, and 90 that holdthe other lenses L3, L4, and L5, respectively. Moreover, in the camcylinder 170, regions where cam grooves or the like are not formed maybe removed for the purpose of reducing weight. Thus, it can be said thatthe cam cylinder 170 does not form a perfect cylinder.

The zoom ring 130 is attached so as to rotate about the optical axis OAalong the outer circumferential surface of the fixed cylinder 110.Moreover, the zoom ring 130 has the guide groove 132 formed on an innercircumferential surface thereof. The guide groove 132 extends in astraight line in parallel to the optical axis OA direction. The guidegroove 132 engages with the cam follower 152 of the middle cylinder 150.As a result, when the zoom ring 130 is rotated, the middle cylinder 150also rotates about the optical axis OA.

A zoom ring rotation amount detecting unit 133 is disposed on the innerside of the zoom ring 130. The zoom ring rotation amount detecting unit133 detects a rotation amount of the zoom ring 130 rotated by a rotatingoperation from the outside to transmit a rotation amount signalcorresponding to the rotation amount to a barrel control unit 123described later.

The zoom ring rotation amount detecting unit 133 can be formed, forexample, using a rotary scale that rotates together with the zoom ring130 and an optical sensor that counts the scale of the rotary scale.Moreover, the zoom ring rotation amount detecting unit 133 may be formedusing a magnet body that rotates together with the zoom ring 130 and amagnetic body sensor that measures a change in a magnetic fieldoccurring due to movement of the magnetic body. These structures areexamples only and other structures may be used.

Moreover, a focus ring 120 is disposed on the outer circumferentialsurface of the lens barrel 100 on the image side (the right side in thedrawing) of the zoom ring 130. The focus ring 120 is attached so as tobe rotatable about the optical axis OA along the outer circumferentialsurface of the fixed cylinder 110.

A focus ring rotation amount detecting unit 121 is disposed on the innerside of the focus ring 120.

The focus ring rotation amount detecting unit 121 detects a rotationamount of the focus ring 120 rotated by a rotating operation from theoutside to transmit a rotation amount signal corresponding to therotation amount to the barrel control unit 123 described later.

The focus ring rotation amount detecting unit 121 can be formed, forexample, using a rotary scale that rotates together with the focus ring120 and an optical sensor that counts the scale of the rotary scale.Moreover, the focus ring rotation amount detecting unit 121 may beformed using a magnetic body that rotates together with the focus ring120 and a magnetic sensor that measures a change in a magnetic fieldoccurring due to movement of the magnetic body. These structures areexamples only and other structures may be used.

The guide bars 101, 102, and 103 hold the second lens frame 190 at anend portion close to the subject side. FIG. 5A illustrates a holdingstate of the first guide bar 101 and is an enlarged view of a region Xin FIG. 3. FIG. 5B illustrates a holding state of the second guide bar102 and is an enlarged view of a region Y in FIG. 3. FIG. 5C illustratesa holding state of the third guide bar 103 and is an enlarged view of aregion Z in FIG. 4. FIG. 6 is a diagram illustrating only the secondlens frame 190 in FIG. 2.

As illustrated in FIGS. 5A, 5B, and 5C, the guide bars 101, 102, and 103include body portions 101 c, 102 c, and 103 c and small-diameterportions 101 a, 102 a, and 103 a that are provided in the end portionsclose to the subject side of the body portions 101 c, 102 c, and 103 cand that are at the same axis as and narrower than the body portions 101c, 102 c, and 103 c. These small-diameter portions 101 a, 102 a, and 103a are longer than the thickness of the second lens frame 190, and screwholes 101 b, 102 b, and 103 b are formed therein so as to penetrate fromthe subject side to the image side.

On the other hand, as illustrated in FIGS. 2 and 6, three holes 201,202, and 203 are formed at an equal interval in the circumferentialdirection so that the distance in the radial direction from the center(optical axis OA) of the second lens frame 190 is substantially equal.That is, the holes 201, 202, and 203 are disposed to form anapproximately regular triangle when these three holes are connected.

(First Hole)

The first hole 201 among the three holes is a circular hole formed abovethe second lens frame 190 in the positive Y direction and has a diameterslightly larger than the diameter of the small-diameter portion 101 a.

As illustrated in FIGS. 5A to 5C, the small-diameter portion 101 a ofthe first guide bar 101 is fitted to the first hole 201, and a screw 301having a screw portion 301 a that screws with the screw hole 101 b isinserted from the subject side.

On the outer circumference of the small-diameter portion 101 a, abiasing spring 401 is disposed between an end portion between thesmall-diameter portion 101 a and the body portion 101 c and one sidewall of the lens frame 190. Moreover, on the outer circumference of thesmall-diameter portion 101 a, the biasing spring 401 is also disposedbetween a screw head 301 b and the other side wall of the lens frame190. As a result, the lens frame 190 is biased in the optical axisdirection by the biasing spring 401.

In the present embodiment, although a wave washer is used as the biasingspring 401, the present invention is not limited to this and anotherbiasing member such as a coil spring may be used. Moreover, in thepresent embodiment, although the biasing springs 401 are disposed onboth sides of the lens frame 190, the biasing spring 401 may be disposedon any one side.

(Second Hole)

The second hole 202 is a long hole formed on the negative X side and thenegative Y side of the second lens frame 190, and a length in a majoraxis thereof is larger than the diameter of the first hole 201.

As illustrated in FIG. 6, the second hole 202 is formed so that astraight line extending in the major axis of the second hole 202 passesthe center of the first hole 201.

The small-diameter portion 102 a of the second guide bar 102 is fittedto the second hole 202 with a minimum necessary gap, and a screw 302having a screw portion 302 a that screws with the screw hole 102 b isinserted from the subject side.

On the outer circumference of the small-diameter portion 102 a, biasingsprings 402 are disposed at the same two positions as the small-diameterportion 101 a.

As described above, the second hole 202 is a long hole and is formed sothat a straight line extending in the major axis thereof passes thecenter of the first hole 201. Thus, the second guide bar 102 can beinserted in the second hole 202 even when a relative distance to thefirst guide bar 101 has a small error from a design value.

(Third Hole)

The third hole 203 is a circular hole formed on the positive X side andthe negative Y side of the second lens frame 190 and has a sufficientgap necessary for avoiding redundant constraint in relation to thesmall-diameter portion 103 a of the third guide bar 103.

Similarly to the first and second guide bars 101 and 102, thesmall-diameter portion 103 a is inserted in the third hole 203, and ascrew 303 having a screw portion 303 a that screws with the screw hole103 b is inserted from the subject side.

On the outer circumference of the small-diameter portion 103 a, biasingsprings 403 are disposed at the same two positions as the small-diameterportion 101 a.

As described above, since the diameter of the third hole 203 is largerthan that of the small-diameter portion 103 a of the third guide bar 103and the first hole 201, the third guide bar 103 can be inserted in thethird hole 203 even when a relative distance of the third guide bar 103to the first and second guide bars 101 and 102 has a small error from adesign value.

According to the present embodiment, due to the screws 301, 302, and303, the first, second, and third guide bars 101, 102, and 103 areprevented from being removed from the second lens frame 190.

Moreover, the first, second, and third guide bars 101, 102, and 103 areelastically fixed to the second lens frame 190.

Thus, the first, second, and third guide bars 101, 102, and 103 movetogether with the second lens frame 190 in the optical axis directionand the direction vertical to the optical axis.

Further, on the outer circumferences of the small-diameter portions 101a, 102 a, and 103 a, the biasing springs 401, 402, 403 are disposed onboth sides of the lens frame 190, respectively. Due to this, the lensframe 190 is not completely fixed to the guide bars 101, 102, and 103but is elastically fixed in a state of being biased in the optical axisdirection. Therefore, the second lens frame 190 can be tilted to someextent in relation to the first, second, and third guide bars 103, 102,and 103.

Returning to FIGS. 1, 3, and 4, the lens barrel 100 includes the first,second, and third linear actuators 125A, 125B, and 125C on the subjectside on the inner side of the fixed cylinder 110.

The linear actuators 125A, 125B, and 125C are arranged on the image sideof the supporting portions 114A, 114B, and 114C that support the guidebars 101, 102, and 103 on the subject side, respectively. The linearactuators 125A, 125B, and 125C can be driven so as to move the guidebars 101, 102, and 103 in the optical axis OA direction.

The linear actuators 125A, 125B, and 125C may have the same output powerand may have different output power.

When the guide bars 101, 102, and 103 are driven by the linear actuators125A, 125B, and 125C, the second lens frame 190 combined to the guidebars 101, 102, and 103 and the lens L2 held by the lens frame 190 aremoved in the optical axis OA direction.

A moving mechanism of the lens L2 by the linear actuators 125A, 125B,and 125C is completely independent from moving mechanisms of the otherlenses L1, L3, L4, and L5. Thus, the lens L2 can move independentlyregardless of the other lenses L1, L3, L4, and L5.

The lens barrel 100 further includes first, second, and third positiondetecting units 127A, 127B, and 127C that are disposed on the image sideon the inner side of the fixed cylinder 110 so as to detect thepositions of the first, second, and third guide bars 101, 102, and 103,respectively.

The first, second, and third position detecting units 127A, 127B, and127C are arranged on the image side of supporting portions 116A, 116B,and 116C that support the guide bars 101, 102, and 103 on the imageside, respectively.

The position detecting units 127A, 127B, and 127C can detect an absoluteposition of the lens barrel 100 in relation to the fixed cylinder 110.For example, the position detecting units 127A, 127B, and 127C areformed, for example, using a linear scale that moves integrally with thefirst guide bar 101 and an optical sensor that counts the scale of thelinear scale. Moreover, the position detecting units 127A, 127B, and127C may be formed using a magnetic body that moves together with thefirst guide bar 101 and a magnetic sensor that measures a change in amagnetic field occurring due to movement of the magnetic body. However,these structures are examples only and other structures may be used.

When the linear actuators 125A, 125B, and 125C move the guide bars 101,102, and 103, respectively, the position detecting units 127A, 127B, and127C are operated to detect the positions of the guide bars 101, 102,and 103, respectively.

The barrel control unit 123 controls the driving of the linear actuators125A, 125B, and 125C based on the rotation amount information of thezoom ring 130 input from the zoom ring rotation amount detecting unit133, the rotation amount information of the focus ring 120 input fromthe focus ring rotation amount detecting unit 121, and the focusinformation input from the camera body 10.

Moreover, the barrel control unit 123 includes an internal memory 123 a.

The lenses L3, L4, and L5 have a configuration in which the third,fourth, and fifth lens frames 70, 80, and 90 are connected to the camcylinder 170 rotated by rotation of the zoom ring 130 by an interlockingmechanism. An existing optional driving mechanism can be used as theinterlocking mechanism. In this way, the lenses L3, L4, and L5 are movedin a predetermined relation in the optical axis OA direction by arotating operation of the zoom ring 130, respectively.

A cover cylinder 165 attached at the same axis as the fixed cylinder 110is disposed between the outer cylinder 161 and the zoom ring 130. Thecover cylinder 165 can advance and retract along the outer cylinder 161and seals a space between the outer cylinder 161 and the zoom ring 130.In this way, the cover cylinder 165 prevents dust from entering into thelens barrel 100.

The lens barrel 100 having the above-described configuration operates inthe following manner when the zoom ring 130 is rotated, and the focaldistance changes continuously between a wide-side end and a tele-sideend.

When the zoom ring 130 is rotated from the outside so that the lensbarrel 100 rotates about the optical axis OA, rotation driving force istransmitted to the middle cylinder 150 via the cam follower 152 thatengages with the guide groove 132. When the middle cylinder 150 isrotated, driving force is transmitted from the cam groove 154 to the camfollower 162 of the outer cylinder 161.

Upon receiving the driving force, the cam follower 162 is guided to thestraight groove 146 of the inner cylinder 140 to move straightly (movesin the optical axis OA direction). As a result, the first lens frame 160combined to a distal end of the outer cylinder 161 and the lens L1 heldby the first lens frame 160 integrally move straightly.

Moreover, when the middle cylinder 150 rotates, rotation driving forceis also transmitted to the cam follower 172 that engages with thestraight groove 156. As a result, the cam cylinder 170 rotates about theoptical axis OA along the inner circumferential surface of the fixedcylinder 110.

When the cam cylinder 170 rotates, the driving force is transmitted tothe cam follower 142 that engages with the cam groove 171. The camfollower 142 is guided to the straight groove 111 of the fixed cylinder110 to move straightly. As a result, the inner cylinder 140 and themiddle cylinder 150 that engages with the inner cylinder 140 with theaid of the engagement circumferential groove 158 move straightly.

Moreover, when the cam cylinder 170 rotates, the cam cylinder 170 itselfmoves straightly by being driven by the cam pin 112 of the fixedcylinder 110 that engages with the cam groove 173.

In this manner, when the zoom ring 130 is rotated, the lenses L1, L3,L4, and L5 move so that the mutual gap changes.

Moreover, when the zoom ring 130 is rotated, the barrel control unit 123controls the linear actuators 125A, 125B, and 125C based on the rotationamount of the zoom ring 130 input from the zoom ring rotation amountdetecting unit 133 to move the lens L2 to a predetermined positioncorresponding to the rotation of the zoom ring 130.

By these series of operations, the lens barrel 100 is extended orcontracted so that the gap between the lenses L1, L2, L3, and L4 and thelens L5 changes and the focal distance of the entire optical systemchanges.

Moreover, when the focus ring 120 is rotated, the lens barrel 100operates in the following manner and the focus distance changes.

That is, when the focus ring 120 is rotated, the rotation amountinformation of the focus ring 120 is input from the focus ring rotationamount detecting unit 121 to the barrel control unit 123. The barrelcontrol unit 123 controls the linear actuators 125A, 125B, and 125Cbased on the rotation amount information of the focus ring 120.

As a result, the guide bars 101, 102, and 103 guide the movement in theoptical axis OA direction of the second lens frame 190 holding the lensL2 so that the lens L2 moves in the optical axis OA direction and thefocus distance changes.

As described above, since a moving mechanism of the lens L2 by thelinear actuators 125A, 125B, and 125C is completely independent frommoving mechanisms of the other lenses L1, L3, L4, and L5, the lenses L1,L3, L4, and L5 other than the lens L2 will not move when the focus ring120 is rotated.

Here, in the present embodiment, the second lens frame 190 (that is, asecond lens unit L2) is supported by the guide bars 101, 102, and 103,respectively.

Moreover, the positions of the guide bars 101, 102, and 103 at which thesecond lens frame 190 is supported are determined by the small-diameterportions 101 b, 102 b, and 103 b of the guide bars 101, 102, and 103.

On the outer circumference of the small-diameter portions 101 a, 102 a,and 103 a, the biasing spring 401 is disposed between the step portionbetween the small-diameter portions 101 a, 102 a, and 103 a and the bodyportions 101 c, 102 c, and 103 c and one side wall of the lens frame190. Moreover, on the outer circumference of the small-diameter portions101 a, 102 a, and 103 a, the biasing spring 401 is also disposed betweenthe screw heads 301 b, 302 a, and 303 a and the other side wall of thelens frame 190. As a result, the lens frame 190 is biased in the opticalaxis direction by the biasing springs 401, 402, and 403.

Thus, when the positional relation of the three guide bars 101, 102, and103 in the optical axis direction is changed, the second lens frame 190can be tilted with respect to the optical axis.

Here, the lens barrel 100 includes a plurality of lenses as illustratedin the drawing. When the lens barrel 100 is assembled, manufacturingerrors and assembling errors are accumulated. After the lens barrel ismanufactured, these errors are accumulated and the optical performanceof the lens barrel 100 may deteriorate with tilting and shifting oflenses.

However, in the present embodiment, the lens L2 can be tilted withrespect to the optical axis by changing the relative positional relationof the guide bars 101, 102, and 103, respectively. With this tilting,deterioration of the optical performance resulting from theseaccumulated errors can be eliminated.

In the present embodiment, images are captured in advance by theimage-capturing element 16 at a plurality of positions of the lenses L2in the optical axis direction, the information on the relative positionof the guide bars 101, 102, and 103 at which the lens L2 is tilted suchthat the optical performance (that is, the performance of the opticalsystem formed of the lenses L1, L2, L3, and L4 and the lens L5) of thelens barrel 100 is optimized is calculated, and the relative positioninformation is stored in the memory 123 a of the barrel control unit123.

When the focal distance of the entire optical system changes with theoperation of the zoom ring 130, the positions in the optical axisdirection of the lenses L1, L2, L3, and L4 and the lens L5 change. Thatis, when the focal distance changes, the optical performance of theentire optical system may change. Thus, images may be captured inadvance by the image-capturing element 16 at a plurality of focaldistances, the information on the relative position of the guide bars101, 102, and 103 at which the lens L2 is tilted such that the opticalperformance is optimized may be calculated, and the relative positioninformation may be stored in the memory 123 a of the barrel control unit123.

Further, images may be captured at a plurality of positions in theoptical axis direction of the lens L2, the information on the relativeposition of the guide bars 101, 102, and 103 at which the lens L2 istilted such that the optical performance is optimized may be calculated,and the relative position information may be stored in the memory 123 aof the barrel control unit 123.

In an actual image-capturing operation, the relative positional relationof the guide bars 101, 102, and 103 is changed based on the positioninformation from the position detecting units 127A, 127B, and 127C basedon the information stored in the memory 123 a according to the position(or the focal distance) of the lens L2 so that the lens L2 is tiltedoptimally according to the position (or the focal distance) of the lensL2.

When control is performed so that the lens L2 is tilted optimallyaccording to the focal distance (or both the position of the lens L2 andthe focal distance), a detecting unit that detects the rotation amountof the zoom ring 130 may be provided and the detected rotation amountinformation may be input to the barrel control unit 123.

According to the present embodiment, the following advantages areobtained.

(1) Three linear actuators 125A, 125B, and 125C that drive three guidebars 101, 102, and 103 in the optical axis direction, respectively, areprovided. These linear actuators 125A, 125B, and 125C are controlled toadjust the driving amount in the optical axis direction of the threeguide bars 101, 102, and 103 so that the lens frame 190 is tilted from adirection orthogonal to the optical axis. In this way, the lens frame190 can be tilted according to the position in the optical axisdirection of the focusing lens L2 such that the optical performance ofthe lens barrel 100 is optimized.

(2) The guide bars 101, 102, and 103 guide the movement in the opticalaxis OA direction of the second lens frame 190 holding the lens L2. Inthis case, since the second lens frame 190 is held by the three guidebars 101, 102, and 103, rotation of the lens L2 in the directionvertical to the optical axis is prevented. As a result, the lenses canbe driven in a well-balanced manner.

(3) The first hole 201 formed in the second lens frame 190 is fitted sothat the first guide bar 101 does not move in a direction vertical tothe optical axis in relation to the second lens frame 190, the secondhole 202 is a long hole, and the third hole has a diameter larger thanthe diameter of the small-diameter portion of the guide bar in which thesecond lens frame 190 is inserted.

Thus, even when the relative positions of the guide bars 101, 102, and103 in a plane vertical to the optical axis are shifted slightly due tomanufacturing errors, the guide bars 101, 102, and 103 are reliablyinserted in the holes 201, 202, and 203 of the second lens frame 190.That is, the guide bars 101, 102, and 103 are not constrainedredundantly.

Second Embodiment

Hereinafter, a second embodiment of the present invention will bedescribed. The same constituent components as the first embodiment willbe denoted by the same reference numerals, and the description thereofwill not be provided.

FIG. 7 is a diagram conceptually illustrating a camera 1 which is anembodiment according to the present invention. FIG. 8 is a diagram of alens frame 190′ of a lens barrel 100′ of FIG. 7 when seen from thedirection indicated by A-A. FIG. 9 is a cross-sectional view of the lensbarrel 100′ taken along line B-B in FIG. 8. FIG. 10 is a cross-sectionalview of the lens barrel 100′ taken along line C-C in FIG. 8. FIG. 7 is across-sectional view taken along line D-D in FIG. 8.

Guide bars 101′, 102′, and 103′ of the second embodiment hold the secondlens frame 190′ at an end portion close to the subject side.

FIG. 11A illustrates a holding state of the first guide bar 101′ and isan enlarged view of a region X in FIG. 9. FIG. 11B illustrates a holdingstate of the second guide bar 102′ and is an enlarged view of a region Yin FIG. 9. FIG. 11C illustrates a holding state of the third guide bar103′ and is an enlarged view of a region Z in FIG. 9.

FIG. 12 is a diagram illustrating only the second lens frame 190′ ofFIG. 8.

Unlike the first embodiment, in the second embodiment, one positiondetecting unit (movement amount detecting unit) 127′ is provided in thefirst guide bar 101′.

Moreover, as illustrated in FIGS. 11A, 11B, and 11C, unlike the firstembodiment, small-diameter portions 101 a′, 102 a′, and 103 a′ that areprovided in the end portions closer to the subject side of body portions101 c′, 102 c′, and 103 c′ and that are at the same axis as and thinnerthan the body portions 101 c′, 102 c′, and 103 c′ have approximately thesame length as the thickness of the second lens frame 190′.

Similarly to the first embodiment, in the second embodiment, three holes201′, 202′, and 203′ are formed in the second lens frame 190′ asillustrated in FIGS. 8 and 12. Hereinafter, the difference of theseholes from those of the first embodiment will be described.

(First Hole)

Although the first hole 201′ of the three holes is a circular holeformed above the second lens frame 190′ in the positive Y directionsimilarly to the first embodiment, the first hole 201′ has substantiallythe same diameter as the diameter of the small-diameter portion 101 a′unlike the first embodiment. Moreover, the biasing spring 401 of thefirst embodiment is not provided.

An end surface of the first guide bar 101′ is in contact with a sidesurface of the screw 301.

Moreover, a minimum necessary gap is provided between the small-diameterportion 101 a′ and the second lens frame 190′ in the optical axisdirection so that the first guide bar 101′ is not constrainedredundantly when the second lens frame 190′ moves in the optical axisdirection according to a zooming operation. However, the presentinvention is not limited to this, and unlike the second and third guidebars 102′ and 103′ described later, in the first guide bar 101′, thesmall-diameter portion 101 a′ and the second lens frame 190′ may befixed without providing a gap therebetween in the optical axisdirection.

(Second Hole)

The second hole 202′ is a U-shaped groove 202′ formed on the negative Xside and the negative Y side of the second lens frame 190′. The secondhole 202′ has substantially the same width (distance between facing sidesurfaces) as the diameter of the small-diameter portion 102 a′.

The U-shaped groove 202′ is formed so that a straight line P (asymmetric axis on a cross-section that forms the U-shape of the U-shapedgroove) extending from the center in the width direction of the openingto the center of the bottom of the groove passes through the center ofthe first hole 201′.

The small-diameter portion 102 a′ of the second guide bar 102′ is fittedto the second hole (U-shaped groove) 202′. Here, an end surface of theguide bar 102′ is in contact with a side surface of the screw 302.Moreover, a minimum necessary gap is provided between the small-diameterportion 102 a′ and the second lens frame 190′ in the optical axisdirection so that the second guide bar 102′ is not constrainedredundantly when the second lens frame 190′ moves in the optical axisdirection according to a zooming operation.

As a result, the second guide bar 102′ can be inserted in the secondhole 202′ even when a relative distance to the first guide bar has asmall error from a design value.

(Third Hole)

The third hole 203′ is a circular hole formed on the positive X side andthe negative Y side of the second lens frame 190′ and has a diameterlarger than the small-diameter portion 103 a′ of the third guide bar103′.

An end surface of the third guide bar 103′ is in contact with a sidesurface of the screw 303. Moreover, a minimum necessary gap is providedbetween the small-diameter portion 103 a′ and the second lens frame 190′in the optical axis direction so that the third guide bar 103′ is notconstrained redundantly when the second lens frame 190′ moves in theoptical axis direction according to a zooming operation.

As a result, the third guide bar 103′ can be inserted in the third hole203′ even when a relative distance of the third guide bar 103′ to thefirst and second guide bars 101′ and 102′ has a small error from adesign value.

The linear actuators 125A′, 125B′, and 125C′ operate by the drivingamount corresponding to the driving signal output from a barrel controlunit 123′ described later to drive the guide bars 101′, 102′, and 103′,respectively.

In the present lens barrel 100′ having the above-describedconfiguration, the movement of the lens L2 during changing of focaldistance (zooming) and focusing is performed by the linear actuators125A′, 125B′, and 125C′ controlled by the barrel control unit 123′.

The position detecting unit 127′ is arranged on the image side of thesupporting portion 114 that supports the first guide bar 101′ on theimage side. The position detecting unit 127′ operates when the linearactuator 125 moves the first guide bar 101′, detects a movement amountin the optical axis OA direction of the first guide bar 101′ in relationto the fixed cylinder 110, and transmits a movement amount signalcorresponding to the detected movement amount to the barrel control unit123′.

The barrel control unit 123′ controls the driving of the linearactuators 125A′, 125B′, and 125C′ based on the rotation amountinformation of the zoom ring 130 input from the zoom ring rotationamount detecting unit 133, the rotation amount information of the focusring 120 input from the focus ring rotation amount detecting unit 121,and the movement amount information of the first linear actuator 125A′input from the position detecting unit 127′.

That is, the barrel control unit 123′ stores computation information forcomputing the position of the lens L2 in relation to the rotation amountof the zoom ring 130, computes the position of the lens L2 based on therotation amount information input from the zoom ring rotation amountdetecting unit 133 when the zoom ring 130 rotates, and drives the linearactuators 125A′, 125B′, and 125C′ so as to move the lens L2 to thecomputed position.

Moreover, the barrel control unit 123′ stores computation informationfor computing the position of the lens L2 in relation to the rotationamount of the focus ring 120, computes the position of the lens L2 basedon the rotation amount information input from the focus ring rotationamount detecting unit 121 when the focus ring 120 rotates, and drivesthe linear actuators 125A′, 125B′, and 125C′ so as to move the lens L2to the computed position.

Here, a predetermined position of the lens L2 corresponding to therotation of the zoom ring 130 is a position at which the lens L2 ismoved by an amount which is the sum of a movement amount required forchanging the focal distance based on the rotation amount of the zoomring 130 and a focus adjustment correction amount for not changing thefocus distance (focusing position).

That is, in the present lens barrel 100 in which the lens L2 is afocusing lens, when the focal distance changes, the moving distance(focus movement range) of the lens L2 ranging from the closest distanceto the infinity changes (the moving distance increases as the focaldistance increases). Due to this, during changing of focal distance(during a zooming operation), the barrel control unit 123′ moves thelens L2 by an amount which is the sum of a movement amount correspondingto a change in the focal distance thereof and a focus adjustmentcorrection amount for eliminating a shift of the focus position beforethe zooming operation is performed. In this way, even when the zoomingoperation is performed, the focus position is maintained, and a focusshift does not occur.

Here, the barrel control unit 123′ controls the linear actuators 125A′,125B′, and 125C′ so that the lens L2 moves between the nearest distanceand the infinity by the always constant rotation amount (rotation angle)of the focus ring 120 regardless of the focal distance. That is, asdescribed above, in the lens barrel 100′, although the focus movementrange (movement amount) of the lens L2 ranging from the nearest distanceto the infinity changes according to the focal distance, the barrelcontrol unit 123′ performs control so that the ratio of the movementamount of the lens L2 to the rotation amount of the focus ring 120 ischanged according to the focal distance, and the rotation amount of thefocus ring 120 between the nearest distance and the infinity is alwaysconstant regardless of the focal distance.

Moreover, the barrel control unit 123′ corrects a driving signal to begenerated by referring to the movement amount signal received from theposition detecting unit 127′. In this way, it is possible to correct amovement amount error of the guide bars 101′, 102′, and 103′ resultingfrom disturbance to accurately move the lens L2 and to quickly bring thelens barrel 100′ into a focusing state with high accuracy.

When the lens barrel 100′ is brought into a focusing state according tothe auto-focus control of the control device 18 of the camera body 10illustrated in FIG. 1, the focus ring 120 is not rotated. In such acase, the movement amount of the lens L2 required for bringing the lensbarrel 100′ into a focusing state is transmitted from the control device18 of the camera body 10 to the barrel control unit 123′ as a requiredmovement amount signal. Upon receiving the required movement amountsignal, the barrel control unit 123′ generates a driving signal suitablefor the required movement amount and supplies the same to the linearactuators 125A′, 125B′, and 125C′.

According to the present embodiment, the following advantages areobtained.

(1) The guide bars 101′, 102′, and 103′ guide the movement in theoptical axis OA direction of the second lens frame 190′ holding the lensL2. In this case, since the second lens frame 190′ is held by the threeguide bars 101′, 102′, and 103′, rotation of the lens L2 in thedirection vertical to the optical axis is prevented. As a result, thelenses can be driven in a well-balanced manner.

(2) Although the guide bars 101′, 102′, and 103′ can move in the opticalaxis direction in relation to the fixed cylinder 110, the guide bars101′, 102′, and 103′ are held so that the movement in the directionvertical to the optical axis is restricted. That is, the relativepositional relation of the guide bars 101′, 102′, and 103′ in thedirection vertical to the optical axis is fixed by the supportingportion 114 of the fixed cylinder 110. However, the relative positionalrelation of these guide bars may be different from one lens barrel toanother due to manufacturing errors or the like.

Due to this, when the holes 201′, 202′, and 203′ of the second lensframe 190′ in which the guide bars 101′, 102′, and 103′ are inserted arenot formed so as to allow small manufacturing errors, it may not bepossible to insert the guide bars 101′, 102′, and 103′ in the holes ofthe second lens frame 190′.

According to the present embodiment, the first hole 201′ formed in thesecond lens frame 190′ is fitted so that the first guide bar 101′ doesnot move in the direction vertical to the optical axis in relation tothe second lens frame 190′, the second hole 202′ is a U-shaped groove,and the third hole has a diameter larger than that of the small-diameterportion of the guide bar in which the second lens frame 190′ isinserted.

Thus, even when the relative positions of the guide bars 101′, 102′, and103′ in a plane vertical to the optical axis are shifted slightly due tomanufacturing errors, the guide bars 101′, 102′, and 103′ are reliablyinserted in the holes 201′, 202′, and 203′ of the second lens frame190′. That is, the guide bars 101′, 102′, and 103′ are not constrainedredundantly.

(3) Since the holes 201′, 202′, and 203′ are formed in such a shape thatthe holes are formed in only minimal directions necessary for absorbingerrors, the lens frame 190′ held by the guide bars 101′, 102′, and 103′will not oscillate.

(4) Since the linear actuators 125A′, 125B′, and 125C′ are formed in theguide bars 101′, 102′, and 103′, respectively, it is possible to securelarge driving force.

(Modifications)

The present invention is not limited to the embodiments described above,but various modifications and changes described below can be made andsuch modifications and changes also fall within the scope of the presentinvention.

(1) In the above-described embodiments, although the linear actuators125 have the same output power, the present invention is not limited tothis.

For example, the first linear actuator 125A may have higher output powerthan the other linear actuators. In this case, in the second embodiment,the first linear actuator 125A′ only is driven when a driving load ofthe second lens frame 190′ is small (for example, the lens is moved in ahorizontal direction), and the second and third linear actuators 125B′and 125C′ may also be driven when the driving load is large (forexample, when the lens is moved in a vertical direction). In this case,when an attitude detecting device is provided in a camera, the number oflinear actuators to be driven may be selected according to the output ofthe attitude detecting device.

(2) In the embodiments described above, the linear actuators 125A, 125B,and 125C that move the guide bars 101, 102, and 103 supporting the lensL2 so as to be movable in the optical axis OA direction are arranged onthe image side of the supporting portion 114 supporting the guide bar102 on the subject side. The position detecting units 127A, 127B, and127C detecting the movement amount in the optical axis OA direction ofthe first guide bar 101 are arranged on the image side of the supportingportion 114A supporting the first guide bar 101 on the image side.However, the arrangement positions of the linear actuators 125A, 125B,and 125C and the position detecting units 127 are not limited to thisbut can be set appropriately.

(3) In the embodiments described above, although the guide bars 101,102, and 103 have the same thickness, the present invention is notlimited to this. For example, the second and third guide bars 102 and103 may be narrower than the first guide bar 101. By using the firstguide bar 101 as a main guide bar and the narrow second and third guidebars as auxiliary guide bars, it is possible to reduce weight ascompared to when the three guide bars have the same thickness.

(4) In the first embodiment, although images are captured in advanceusing the image-capturing element 16 at a plurality of positions in theoptical axis direction of the lens L2, the information on the relativeposition of the guide bars 101, 102, and 103 at which the lens L2 istilted so that the optical performance of the lens barrel 100 isoptimized is stored in the memory 123 a of the barrel control unit 123,images may be captured using the image-capturing element 16 in a state(use state) where the lens barrel 100 is attached to the camera 10, andthe tilt of the lens L2 is controlled so that the optical performance ofthe lens barrel 100 is optimized.

Although the embodiments and the modifications can be appropriatelycombined and used, the detailed description thereof is not providedbecause the configuration of the respective embodiments is obvious fromthe drawings and the description. Further, the present invention is notlimited to the embodiments described above.

What is claimed is:
 1. A lens barrel comprising: a zoom optical systemhaving a lens which can move in an optical axis direction of the zoomoptical system; and a control unit which changes a tilt of the lens withrespect to the optical axis direction based on a focal distance of thezoom optical system.
 2. The lens barrel according to claim 1, whereinthe control unit changes the tilt of the lens with respect to theoptical axis direction upon movement of the lens in the optical axisdirection during zooming or focusing.
 3. The lens barrel according toclaim 2, further comprising a storage unit that stores data showing arelationship between a focal distance and the tilt of the lens, whereinthe control unit changes a tilt of the lens with respect to the opticalaxis direction based on the data which the storage unit stores and thefocal distance of the zoom optical system.
 4. The lens barrel accordingto claim 3, further comprising: a lens holding unit that holds the lens;and a guide bar which is attached to the lens holding unit and providedso as to extend in the optical axis direction, wherein the control unitdrives the guide bar in the optical axis direction.
 5. The lens barrelaccording to claim 4, wherein the control unit changes the tilt of thelens with respect to the optical axis direction by adjusting a drivingamount in the optical axis direction of the guide bar.
 6. The lensbarrel according to claim 5, further comprising a position detectingunit that detects a position of the guide bar in the optical axisdirection, wherein the control unit changes the tilt of the lens basedon the position of the guide bar detected by the position detectingunit.
 7. The lens barrel according to claim 6, further comprising adriving unit that drives the guide bar, wherein the control unitcontrols a driving amount of the driving unit and changes the tilt ofthe lens with respect to the optical axis direction.
 8. The lens barrelaccording to claim 7, wherein the driving unit moves the lens in theoptical axis direction and changes the tilt of the lens with respect tothe optical axis direction.
 9. The lens barrel according to claim 6,further comprising a plurality of guide bars.
 10. An image-capturingdevice comprising the lens barrel according to claim
 1. 11. A lensbarrel comprising: a zoom optical system having a lens which can move inan optical axis direction of the zoom optical system; and a control unitwhich changes a tilt of the lens with respect to the optical axisdirection based on information relating to a position in the opticalaxis direction of the lens.
 12. The lens barrel according to claim 11,further comprising a storage unit that stores data showing arelationship between the information relating to a position in theoptical axis direction of the lens and the tilt of the lens, wherein thecontrol unit changes a tilt of the lens with respect to the optical axisdirection based on the data which the storage unit stores and theposition of the lens in the optical axis direction.
 13. The lens barrelaccording to claim 12, further comprising: a lens holding unit thatholds the lens; and a guide bar which is attached to the lens holdingunit and provided so as to extend in the optical axis direction, whereinthe control unit drives the guide bar in the optical axis direction. 14.The lens barrel according to claim 13, further comprising a driving unitthat drives the guide bar, wherein the control unit controls a drivingamount of the driving unit and changes a tilt of the lens with respectto the optical axis direction.
 15. The lens barrel according to claim14, wherein the control unit controls the driving amount of the drivingunit based on a zoom amount of the zoom optical system.
 16. The lensbarrel according to claim 14, wherein the control unit controls thedriving amount of the driving unit based on focus information of thezoom optical system.
 17. The lens barrel according to claim 14, whereinthe control unit controls the driving amount of the driving unit basedon a position of the lens.
 18. The lens barrel according to claim 13,further comprising a position detecting unit that detects a position ofthe guide bar in the optical axis direction, wherein the control unitchanges the tilt of the lens based on the position of the guide bardetected by the position detecting unit.
 19. A method for driving a lensbarrel including a zoom optical system having a lens which can move inan optical axis direction of the zoom optical system, comprising: acontrol unit changing a tilt of the lens in the optical axis directionbased on a focal distance of the zoom optical system.
 20. A method fordriving a lens barrel including a zoom optical system having a lenswhich can move in an optical axis direction of the zoom optical system,comprising: a control unit changing a tilt of the lens in the opticalaxis direction based on information relating to a position of the lensin the optical axis direction.